With progress in enzyme-utilizing industries in recent years, various techniques have been proposed for immobilizing enzymes on water-insoluble supports to increase their utility. It would be desirable to immobilize enzymes, which have been utilized as water soluble catalysts, to keep the enzymes from free diffusion and efflux into the reaction substrate, thus enabling their recovery and reuse, as well as enabling continuous reaction by charging them into the columns. The techniques for immobilizing enzymes proposed so far include immobilization of an enzyme by the entrapment in a gelled, water-insoluble, high molecular weight substance (for example, polyacrylamide), coupling of the enzyme to a water-insoluble support (for example, porous glass) and the like. It is, however, difficult at present to put the above techniques into practical use, because their application to the immobilization of intracellular enzymes requires the steps of rupturing the microbial cells containing the enzymes and/or ultrasonic treatment, freeze-thaw grinding, organic solvent treatment, autolysis and the like to isolate the enzymes from the cells, which techniques present efficiency and process problems. More specifically, gelled cells prepared from ruptured cells or autolyzed cells are deficient in the mechanical strength required for using the cells as a column packing. In view of the foregoing, various methods have been proposed for the immobilization of intracellular enzymes including coupling of enzymatically active microbial cells to other protein-like substances and entrapment of such cells in the lattice of a high molecular substance. None of these prior art procedures, however, have proven satisfactory.